Multi-subframe grant with scheduling of both data and control channels

ABSTRACT

A method implemented in a wireless device includes receiving an uplink grant from a network node indicating to the wireless device at least one data subframe and at least one control subframe. The at least one data subframe is one where the wireless device is scheduled to transmit a channel for carrying a data stream and optional control data, and the at least one control subframe is one where the wireless device is scheduled to transmit a channel for carrying control data only. The method further includes transmitting in at least one of the at least one data subframe and the at least one control subframe indicated by the uplink grant.

TECHNICAL FIELD

Embodiments of the subject matter disclosed herein generally relate to acellular communications network, and, more particularly, to methods anddevices for enabling wireless communication devices to operate inunlicensed radio spectrums in addition to licensed spectrums.

BACKGROUND

Wireless communication may take place within in a dedicated spectrum.For example, up to now, the spectrum used by Long-Term Evolution (LTE)cellular communications networks is dedicated to LTE. This has theadvantage that an LTE system does not need to take into account anyspectrum coexistence issues with other uses of the spectrum, and thatspectrum efficiency can be maximized. However, the spectrum allocated toLTE is limited which may not be able to meet the ever increasing demandfor larger throughput from applications and services.

Accordingly, consideration is being given to enabling wirelesscommunication devices to be operable in unlicensed radio spectrums inaddition to licensed spectrums. For example, “Licensed-Assisted Access”(LAA) may allow LTE equipment to also operate in the unlicensed 5 GHzradio spectrum. The unlicensed 5 GHz spectrum may be used as acomplement to the licensed spectrum. Accordingly, devices may connect inthe licensed spectrum (primary cell or PCell) and use carrieraggregation to benefit from additional transmission capacity in theunlicensed spectrum (secondary cell or SCell). Further, it isconceivable that standalone operation of LTE in an unlicensed spectrummay also be possible.

However, the present inventor has recognized that transmissions in anunlicensed spectrum present challenges. An unlicensed spectrum can, bydefinition, be simultaneously used by multiple different technologies.Therefore, communication by wireless devices in unlicensed spectrumsneeds to consider coexistence issues with other systems that may utilizethe same spectrum, such as IEEE 802.11 (Wi-Fi). For example, operatingLTE in the same manner in unlicensed spectrum as in licensed spectrumcan seriously degrade the performance of Wi-Fi as Wi-Fi will nottransmit once it detects that the channel is occupied.

Accordingly, it would be desirable to provide systems and methods thatavoid the afore-described problems and drawbacks and which, morespecifically, provide for methods and devices enabling wirelesscommunication devices to operate in unlicensed radio spectrums inaddition to licensed spectrums.

SUMMARY

In various embodiments described in this document, a multi-subframegrant indicates to a wireless device one or more data and controlsubframes for communication in an unlicensed radio spectrum in additionto or in place of a licensed spectrum.

According to an embodiment there is a method implemented in a wirelessdevice. The method includes receiving an uplink grant from a networknode indicating to the wireless device at least one data subframe and atleast one control subframe. The at least one data subframe is one wherethe wireless device is scheduled to transmit a channel for carrying adata stream and optional control data, and the at least one controlsubframe is one where the wireless device is scheduled to transmit achannel for carrying control data only. The method further includestransmitting in at least one of the at least one data subframe and theat least one control subframe indicated by the uplink grant.

According to another embodiment there is a wireless device. The wirelessdevice includes a receiver, a transmitter, at least one processor, and amemory. The memory stores instructions executable by the at least oneprocessor for receiving, using the receiver, an uplink grant from anetwork node indicating to the wireless device at least one datasubframe and at least one control subframe. The at least one datasubframe is one where the wireless device is scheduled to transmit achannel for carrying a data stream and optional control data, and the atleast one control subframe is one where the wireless device is scheduledto transmit a channel for carrying control data only. The memory storesinstructions executable by the at least one processor for transmitting,using the transmitter, in at least one of the at least one data subframeand the at least one control subframe indicated by the uplink grant.

According to yet another embodiment there is a method implemented in anetwork node. The method includes transmitting an uplink grantindicating to a wireless device at least one data subframe and at leastone control subframe. The at least one data subframe is one where thewireless device is scheduled to transmit a channel for carrying a datastream and optional control data, and the at least one control subframeis one where the wireless device is scheduled to transmit a channel forcarrying control data only. The method further includes receiving, froma wireless device having received the uplink grant, transmissions in atleast one of the at least one data subframe and the at least one controlsubframe indicated by the uplink grant.

According to yet another embodiment there is a network node. The networknode includes a receiver, a transmitter, at least one processor, and amemory. The memory stores instructions executable by the at least oneprocessor for transmitting, using the transmitter, an uplink grantindicating to a wireless device at least one data subframe and at leastone control subframe. The at least one data subframe is one where thewireless device is scheduled to transmit a channel for carrying a datastream and optional control data, and the at least one control subframeis one where the wireless device is scheduled to transmit a channel forcarrying control data only. The memory stores instructions executable bythe at least one processor for receiving, using the receiver, from awireless device having received the uplink grant, transmissions from thewireless device in at least one of the at least one data subframe andthe at least one control subframe indicated by the uplink grant.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate one or more embodiments and,together with the description, explain these embodiments. On thedrawings,

FIG. 1 is a schematic representation of an exemplary LTE downlinktime-frequency grid;

FIG. 2 is a schematic representation of an exemplary LTE time-domainstructure;

FIG. 3 is a schematic representation of an exemplary downlink subframe;

FIG. 4 is a schematic representation of an exemplary uplink subframe;

FIG. 5 is a schematic representation of carrier aggregation;

FIG. 6 is a schematic representation of a Listen Before Talk (LBT)mechanism of Wi-Fi;

FIG. 7 is a schematic representation of Licensed-Assisted Access (LAA)to unlicensed spectrum using LTE carrier aggregation;

FIG. 8 is a schematic representation of UL LAA listen before talktransmission;

FIG. 9 is a schematic representation of two forms of PUCCH transmission;

FIG. 10 is a schematic representation of two multi-subframe grants andone ePUCCH grant being sent on a DL to schedule a burst of UL PUSCHtransmissions followed by an ePUCCH transmission;

FIG. 11 is a schematic representation of a multi-subframe (MSF) grantaccording to an exemplary embodiment of the present invention;

FIG. 12 is a schematic representation of a network node according to anexemplary embodiment of the present invention;

FIG. 13 is a schematic representation of a wireless device according toan exemplary embodiment of the present invention;

FIG. 14 is a flowchart of an exemplary method implemented by thewireless device of FIG. 13 according to an exemplary embodiment of thepresent invention; and

FIG. 15 is a flowchart of an exemplary method implemented by the networknode of FIG. 12 according to an exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION

The following description of the embodiments refers to the accompanyingdrawings. The same reference numbers in different drawings identify thesame or similar elements. The following detailed description does notlimit the invention. The embodiments to be discussed next are notlimited to the configurations described below, but may be extended toother arrangements as discussed later.

Reference throughout the specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with an embodiment is included in at least oneembodiment of the subject matter disclosed. Thus, the appearance of thephrases “in one embodiment” or “in an embodiment” in various placesthroughout the specification is not necessarily referring to the sameembodiment. Further, the particular features, structures orcharacteristics may be combined in any suitable manner in one or moreembodiments. Features, structures or characteristic described as beingseparate may be combined into a single feature, structure, orcharacteristic. Similarly, features, structures or characteristicsdescribed as being individual may be split into two or more features,structures or characteristics. For example, although a single memory1208 is disclosed with reference to FIG. 12, the memory may be splitinto more than one memory or even more than one type of memory.Likewise, the receiver 1202 and transmitter 1204 disclosed withreference to FIG. 12 may be combined into a transceiver.

The following abbreviations are used in this document:

ACK Acknowledgement

B-IFDMA Block-Interleaved Frequency Division Multiple Access

CA Carrier Aggregation

CC Component Carrier

CCA Clear Channel Assessment

CFI Control Format Indicator

C-PDCCH Common Physical Downlink Control Chanel

CRC Cyclic Redundancy Check

C-RNTI Cell Radio Network Temporary Identifier

CRS Cell-Specific Reference Symbols

CSMA/CA carrier sense multiple access with collision avoidance

CW Contention Window

DCF Distributed Coordination Function

DCI Downlink Control Indicator

DFT Discrete-Fourier-Transform

DIFS DCF Inter-Frame Space

DL Downlink

DMRS Demodulation Reference Signals

DwPTS Downlink Pilot Time Slot

eNB eNodeB

eLAA enhanced Licensed-Assisted Access

EPDCCH Enhanced Physical Downlink Control Channel

ePUCCH extended Physical Uplink Control Channel

FDMA Frequency-Division Multiple Access

HARQ Hybrid Automatic-Repeat-Request

LAA Licensed-Assisted Access

LBT Listen-Before-Talk

LTE Long Term Evolution

LTE-A LTE-Advanced

MCOT Maximum Channel Occupancy Time

MCS Modulation and Coding Scheme

MSF Multi-Subframe Grant

NACK Negative Acknowledgement

PCell Primary Cell

PDCCH Physical Downlink Control Channel

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

OFDM Orthogonal Frequency Division Multiplexing

SC-FDMA Single Carrier Frequency-Division Multiple Access

SCell Secondary Cell

sPUCCH short Physical Uplink Control Channel

SRS Sounding Reference Signals

TXOP Transmission Opportunity

UE User Equipment

UCI Uplink Control Information

UL Uplink

WLAN Wireless Local Area Network

As mentioned above, the present inventor has recognized thattransmissions in an unlicensed spectrum present challenges.

Regulatory requirements may not permit transmissions in an unlicensedspectrum without prior channel sensing. Since the unlicensed spectrum isshared with other radios of similar or dissimilar wireless technologies,a so called listen-before-talk (LBT) method may need to be applied. LBTinvolves sensing the medium for a pre-defined minimum amount of time andbacking off if the channel is busy. By way of non-limiting example, theunlicensed 5 GHz spectrum is mainly used by equipment implementing theInstitute of Electrical and Electronics Engineers (IEEE) 802.11 WirelessLocal Area Network (WLAN) standard. This standard is known under itsmarketing brand “Wi-Fi.”

It should be noted that the present embodiments are discussed inconjunction with the Long Term Evolution (LTE) wireless communicationstandard and Wi-Fi wireless standard. Those skilled in the art willappreciate that the present invention is not limited to application toLTE and Wi-Fi wireless communications systems but can instead be appliedto any such systems.

To provide context for the exemplary embodiments, a discussion of therelevant aspects of LTE and Wi-Fi may be beneficial.

LTE

FIG. 1 is a schematic representation of an exemplary LTE downlinktime-frequency grid 100. LTE uses Orthogonal Frequency DivisionMultiplexing (OFDM) in the downlink and Discrete-Fourier-TransformDFT-spread OFDM (also referred to as single-carrier Frequency-DivisionMultiple Access FDMA) in the uplink. The basic LTE downlink physicalresource can thus be seen as a time-frequency grid 100 as illustrated inFIG. 1, where each resource element 102 corresponds to one OFDMsubcarrier during one OFDM symbol interval. The uplink subframe has thesame subcarrier spacing as the downlink and the same number of SC-FDMAsymbols in the time domain as OFDM symbols in the downlink.

FIG. 2 is a schematic representation of an exemplary LTE time-domainstructure 200. In the time domain, LTE downlink transmissions areorganized into radio frames 202 of 10 ms, each radio frame 202consisting of ten equally-sized subframes 204 of length Tsubframe=1 msas shown in FIG. 2. Each subframe comprises two slots of duration 0.5 mseach, and the slot numbering within a frame ranges from 0 to 19. Fornormal cyclic prefix, one subframe 204 consists of 14 OFDM symbols. Theduration of each symbol is approximately 71.4 μs.

Furthermore, the resource allocation in LTE is typically described interms of resource blocks, where a resource block corresponds to one slot(0.5 ms) in the time domain and 12 contiguous subcarriers in thefrequency domain. A pair of two adjacent resource blocks in timedirection (1.0 ms) is known as a resource block pair. Resource blocksare numbered in the frequency domain, starting with 0 from one end ofthe system bandwidth.

FIG. 3 is a schematic representation of an exemplary downlink subframe300. Downlink transmissions are dynamically scheduled, i.e., in eachsubframe the base station transmits control information about whichterminals data is transmitted to and upon which resource blocks the datais transmitted, in the current downlink subframe. This control signalingis typically transmitted in the first 1, 2, 3 or 4 OFDM symbols in eachsubframe and the number n=1, 2, 3 or 4 is known as the Control FormatIndicator (CFI). The downlink subframe 300 also contains commonreference symbols, which are known to the receiver and used for coherentdemodulation of e.g. the control information. A downlink system withCFI=3 OFDM symbols as control is illustrated in FIG. 3. The referencesymbols shown there are the cell specific reference symbols (CRS) andare used to support multiple functions including fine time and frequencysynchronization and channel estimation for certain transmission modes.

FIG. 4 is a schematic representation of an exemplary uplink subframe400. Uplink transmissions are dynamically scheduled, i.e., in eachdownlink subframe the base station transmits control information aboutwhich terminals should transmit data to the eNB in subsequent subframes,and upon which resource blocks the data is transmitted. The uplinkresource grid is comprised of data and uplink control information in thePhysical Uplink Shared Channel (PUSCH), uplink control information inthe Physical Uplink Control Channel (PUCCH), and various referencesignals such as demodulation reference signals (DMRS) and soundingreference signals (SRS). DMRS are used for coherent demodulation ofPUSCH and PUCCH data, whereas SRS is not associated with any data orcontrol information but is generally used to estimate the uplink channelquality for purposes of frequency-selective scheduling. Note that ULDMRS and SRS are time-multiplexed into the UL subframe 400, and SRS arealways transmitted in the last symbol of a normal UL subframe 400. ThePUSCH DMRS is transmitted once every slot for subframes with normalcyclic prefix, and is located in the fourth and eleventh SC-FDMAsymbols.

In later implementations of LTE, DL or UL resource assignments can alsobe scheduled on the enhanced Physical Downlink Control Channel (EPDCCH).For earlier releases, only the Physical Downlink Control Channel (PDCCH)is available. Resource grants are UE specific and are indicated byscrambling the DCI Cyclic Redundancy Check (CRC) with the UE-specificC-RNTI identifier.

In LTE and LTE-Advanced (LTE-A), each UL transmission on the PUSCH canbe dynamically scheduled using a single UL grant sent in a DL subframewith DCI format 0 on the PDCCH or EPDCCH. The UL transmission takesplace 4 ms after the UL grant is received. Therefore, to dynamicallyschedule N UL PUSCH transmissions over N subframes by a UE, N UL grantsneed to be sent in N DL subframes by the serving cell. Alternatively,periodic UL PUSCH transmissions can be scheduled using semi-persistentscheduling without the need for an UL grant for every UL transmission.

FIG. 5 is a schematic representation carrier aggregation 500. A laterrelease of LTE supports bandwidths larger than 20 MHz. It may bedesirable to assure backwards compatibility with earlier releases thatmay not support bandwidths larger than 20 MHz. This should also includespectrum compatibility. Accordingly, a carrier wider than 20 MHz, shouldappear as a number of LTE carriers to earlier LTE terminals. Each suchcarrier can be referred to as a Component Carrier (CC). In particularfor early deployments of LTE supporting bandwidths larger than 20 MHz,it can be expected that there will be a smaller number of larger than 20MHz capable terminals compared to LTE legacy terminals not supportingbandwidths larger than 20 MHz. Therefore, it is necessary to assure anefficient use of a wide carrier also for legacy terminals, i.e. that itis possible to implement carriers where legacy terminals can bescheduled in all parts of the wideband (greater than 20 MHz) carrier.The straightforward way to obtain this would be by means of CarrierAggregation (CA). CA implies that an terminal supporting bandwidthslarger than 20 MHz can receive multiple CC, where the CC have, or atleast the possibility to have, the same structure earlier LTE releasecarriers. CA 500 is illustrated in FIG. 5. A CA-capable UE is assigned aprimary cell (PCell) which is always activated, and one or moresecondary cells (SCells) which may be activated or deactivateddynamically.

The number of aggregated CC 502 as well as the bandwidth of theindividual CC may be different for uplink and downlink. A symmetricconfiguration refers to the case where the number of CCs in downlink anduplink is the same whereas an asymmetric configuration refers to thecase that the number of CCs is different. It is important to note thatthe number of CCs configured in a cell may be different from the numberof CCs seen by a terminal: A terminal may for example support moredownlink CCs than uplink CCs, even though the cell is configured withthe same number of uplink and downlink CCs.

Wi-Fi

A discussion of the relevant aspects of Wi-Fi is provided in theinterest of context. In typical deployments of Wireless Local AreaNetworks (WLANs), carrier sense multiple access with collision avoidance(CSMA/CA) is used for medium access. This means that the channel issensed to perform a clear channel assessment (CCA), and a transmissionis initiated only if the channel is declared as Idle. In case thechannel is declared as busy, the transmission is essentially deferreduntil the channel is deemed to be Idle.

FIG. 6 is a schematic representation of a Listen Before Talk (LBT)mechanism 600 of Wi-Fi. After a Wi-Fi station A transmits a data frameto a station B, station B shall transmit the ACK frame back to station Awith a delay of 16 μs. Such an ACK frame is transmitted by station Bwithout performing a LBT operation. To prevent another stationinterfering with such an ACK frame transmission, a station shall deferfor a duration of 34 μs (referred to as DIFS) after the channel isobserved to be occupied before assessing again whether the channel isoccupied. Therefore, a station that wishes to transmit first performs aClear Channel Assessment (CCA) by sensing the medium for a fixedduration DIFS. If the medium is idle then the station assumes that itmay take ownership of the medium and begin a frame exchange sequence. Ifthe medium is busy, the station waits for the medium to go idle, defersfor DIFS, and waits for a further random backoff period.

When the medium becomes available, multiple Wi-Fi stations may be readyto transmit, which can result in collision. To reduce collisions,stations intending to transmit select a random backoff counter and deferfor that number of slot channel idle times. The random backoff counteris selected as a random integer drawn from a uniform distribution overthe interval of [0, CW]. The default size of the random backoffcontention window, CWmin, may be set in the IEEE specifications. Itshould be appreciated that collisions can still happen even under thisrandom backoff protocol when there are many stations contending forchannel access. Hence, to avoid recurring collisions, the backoffcontention window size CW is doubled whenever the station detects acollision of its transmission up to a limit, CWmax, which also may beset in the IEEE specifications. When a station succeeds in atransmission without collision, it resets its random backoff contentionwindow size back to the default value CWmin.

Unlicensed Spectrum

Up to now, the spectrum used by LTE is dedicated to LTE. This has theadvantage that LTE system does not need to take into account thecoexistence issue, and that spectrum efficiency can be maximized.However, the spectrum allocated to LTE is limited which cannot meet theever increasing demand for larger throughput from applications/services.Licensed-Assisted Access (LAA) extended LTE to exploit an unlicensedspectrum in addition to the licensed spectrum. Unlicensed spectrum can,by definition, be simultaneously used by multiple differenttechnologies. Therefore, LTE needs to consider the coexistence issuewith other systems such as IEEE 802.11 (Wi-Fi). Operating LTE in thesame manner in the unlicensed spectrum as in the licensed spectrum canseriously degrade the performance of Wi-Fi as Wi-Fi will not transmitonce it detects that the channel is occupied.

One way to utilize the unlicensed spectrum reliably is to transmitessential control signals and channels on a licensed carrier. FIG. 7 isa schematic representation of Licensed-Assisted Access (LAA) tounlicensed spectrum using LTE carrier aggregation. That is, as shown inFIG. 7, a UE 702 is connected to a PCell 704 in the licensed band andone or more SCells 706 in the unlicensed band. A secondary cell inunlicensed spectrum may be referred to herein as licensed-assistedaccess secondary cell (LAA SCell). In the case of standalone operationas in MuLTEfire, no licensed cell is available for uplink control signaltransmissions.

The maximum channel occupancy time (MOOT) of a single DL+UL TransmissionOpportunity (TXOP) in unlicensed bands is limited by regional regulatoryrestrictions. For example, in Europe, EN BRAN is considering thefollowing MOOT rules: Specify max TxOP=6 ms available for 100% of thetime; Specify max TxOP=8 ms is available for 100% of time with a minimumpause of [TBD] μs (in order of 100's μs) after a maximum transmission of6 ms; Specify max TxOP=10 ms is available for [TBD3] % of the time.

In one implementation of eLAA, flexible timing between UL grant and ULtransmission may be supported, with a minimum delay between UL grant andUL transmission being 4 ms. Furthermore, UL PUSCH scheduling maydown-select from one of the following options:

Option 1: Single UL grant in a subframe for a UE can schedule N (N≧1)PUSCH transmissions for the UE in N subframes with single PUSCH persubframe. N may be consecutive or non-consecutive.

Option 2: Single UL grant in a subframe for a UE can schedule singlePUSCH transmission in a single subframe while UE can receive multiple ULgrants in a subframe for PUSCH transmissions in different subframes.

Option 3: Single UL grant in a subframe for a UE can enable the UE totransmit single PUSCH transmission among one of the multiple subframesdepending on UL LBT result.

Two stage grants: A common semi-persistent grant provides high levelinformation (e.g. Resource Block (RB) allocation, Modulation and CodingScheme (MCS) etc.) and a second grant in a subframe for a UE canschedule PUSCH transmissions following options 1 and 2 for certain ULsubframes.

Option 1 above is what may be defined to be a multi-subframe grant.Multi-subframe grants offer significant benefits in terms of reducingcontrol signaling overhead and the need for one DL transmission carryingthe grant for every scheduled UL transmission, which severely degradesUL throughput in unlicensed bands.

In the MuLTEfire Alliance Forum, it has been agreed that multi-subframegrants are supported for UL transmissions.

Regarding UL LBT for the PUSCH after a grant is received, in oneimplementation of eLAA, the UL LBT for self-scheduling can use either asingle CCA duration of at least 25 μs (similar to DL DRS), or a randombackoff scheme with a defer period of 25 μs including a defer durationof 16 us followed by one CCA slot, and a maximum contention window sizethat is to be determined. These options are also applicable forcross-carrier scheduling of UL by another unlicensed SCell. Similar LBToptions are valid for ePUCCH transmission.

FIG. 8 is a schematic representation of UL LAA listen before talktransmission 800. In FIG. 8, the UL grant is sent on an unlicensedcarrier.

Two forms of PUCCH transmission have been defined for MuLTEfire: a shortPUCCH (sPUCCH) 902 comprising between two to six symbols in time, and alonger, enhanced PUCCH (ePUCCH) 904 which spans one subframe in time, asshown in FIG. 9. The sPUCCH 902 occurs immediately after the DwPTSportion of a partial DL subframe as defined in Rel-13 LAA, while theePUCCH 904 can be multiplexed with PUSCH transmissions in 1-ms ULsubframes. Both sPUCCH and ePUCCH utilize an interlaced transmissionmode based on B-IFDMA.

For the triggering of ePUCCH transmissions, both common PDCCH (C-PDCCH)or UL grant (DCI based) based triggers are supported, eNB can use eitheror both mechanisms.

FIG. 10 is a schematic representation of two multi-subframe grants andone ePUCCH grant being sent on a DL to schedule a burst of UL PUSCHtransmissions followed by an ePUCCH transmission. If multi-subframegrants are restricted only to UL PUSCH transmissions, then if the eNBwants to trigger ePUCCH transmissions after a burst of UL subframes,then it will have to potentially interrupt a scheduled UL burst of PUSCHsubframes with a DL transmission that carries a UL grant for the ePUCCH.This will force the introduction of additional gaps for DL and UL LBT,reduce UL throughput, increase overhead, and increase the risk of losingthe medium to Wi-Fi or other LAA nodes. An example of such aninefficient mode of operation is shown in FIG. 10, where four LBT stepsand three UL grants in total are needed to schedule a burst of UL PUSCHtransmissions followed by an ePUCCH transmission.

In MuLTEfire, the ePUCCH transmission may also be triggered using theC-PDCCH. Currently, four reserved bits are available in the C-PDCCH toindicate the status of upcoming UL subframes (for example, whether theyare full or partial UL subframes). Since the C-PDCCH is cell-specific,it does not provide sufficiently granular control to be used asUE-specific multi-subframe grants. Furthermore, using the C-PDCCH totrigger ePUCCH implies that all UEs are forced to send ePUCCH in thesame subframe, and multiplexing of ePUCCH and PUSCH from different UEsin the same subframe is not feasible.

Accordingly, embodiments of the present invention use a single,UE-specific multi-subframe UL grant to schedule a sequence of PUSCH andPUCCH transmissions. This approach is applicable to systems such asMuLTEfire, Rel-14 eLAA, LTE in Rel-14 and beyond with multi-subframegrant support, other versions of LTE in unlicensed bands, and NR/5Gsystems in unlicensed spectrum.

Multi-Subframe UL Grant Indicating Data and Control Subframes

Embodiments of the present invention involve the signaling containedwithin a UE-specific multi-subframe UL grant that indicates to the UEwhether and when to transmit a sequence of one or more PUSCH subframes(i.e., data subframes that may carry a data stream and optionallycontrol data such as UCI) and one or more PUCCH (e.g., ePUCCH) subframes(i.e., control subframes that may carry control data only), where theordering of PUSCH and PUCCH transmissions within the overall sequencemay be arbitrary. It is to be understood that a multi-subframe UL grantmay also convey additional information, such as the following examples:resource/interlace assignment and frequency hopping flag; carrierindicator for cross-carrier scheduling; Modulation and Coding Scheme(MCS); New Data Indicator (NDI); HARQ information and Redundancy Version(RV); Power control command for scheduled PUSCH; Cyclic shift for uplinkDemodulation RS; Flag bits or bit sequences to configure puncturing ofUL subframes for LBT; and Request for transmission of an aperiodic CQIreport or aperiodic SRS transmission.

FIG. 11 is a schematic representation of a multi-subframe (MSF) grant1100 according to an exemplary embodiment of the present invention. TheMSF grant 1100 may contain a bit sequence to indicate the transmissionsequence of one or more PUSCH and ePUCCH transmissions by the same UEover a span of N UL subframes. As a non-limiting example, if the N ULsubframes are contiguous in time and the same UE should transmit PUSCHin N−1 subframes and ePUCCH in 1 subframe, then a bit sequence of 2Nbits may be sent in the MSF grant 1100, with 2 bits schedulinginformation for each subframe. For each bit pair per subframe, eitherthe most significant or least significant bit may indicate whether totransmit PUSCH or ePUCCH (e.g., ‘0’ indicates ePUCCH, ‘1’ indicatesPUSCH), while the other bit may indicate whether to puncture the ULsubframe or not, in order to create a gap for LBT. If the N UL subframesare not contiguous in time, then additional bits may be added toindicate ‘no transmission’. An example scheduling outcome with theproposed MSF grant and N=4 contiguous subframes 1102, 1104, 1106, 1108is shown in FIG. 11. As shown, the first three subframes 1102, 1104,1106 may be data subframes (e.g., PUSCH) that may carry a data streamand optionally control information, while the fourth subframe 1108 maybe a control subframe (e.g., ePUCCH) that may carry control data only.It is not necessary for the ePUCCH to always follow at the end of the ULburst (e.g., in the last subframe 1108 shown in FIG. 11), since aChannel State Information (CSI) report or earlier HARQ ACK/NACK of apreceding DL burst on one or more serving cells may be desired by theserving cell. In such a situation, an uplink grant may include a requestfor a CSI report or HARQ ACK/NACK information. The CSI report or HARQACK/NACK information may be transmitted, for example, in the lastsubframe of a multi subframe sequence.

In another variation of the above example, the indication of ePUCCHtransmission subframe may be done implicitly if the ePUCCH subframe issemi-statically configured to be located after or before the burst ofPUSCH transmissions. In that case, the MSF grant may explicitly indicatethe locations of the PUSCH subframes using a bitmap or range of startand end subframes, while the UE may infer the ePUCCH location to be inthe subframe after the last PUSCH transmission or before the first PUSCHsubframe, for example.

In another exemplary embodiment of a MSF grant, the location of theePUCCH subframe opportunity may be determined based on the cell-specificC-PDCCH and may be common for all UEs, while the UE-specific MSF grantmay indicate to a particular UE if it should transmit or suppress itsePUCCH transmission. This may be achieved for example with a(N+1)-length bit sequence, where the first N bits may indicate whetherPUSCH transmission subframes should occur or not over N contiguoussubframes, while the last bit may indicate whether to transmit orsuppress ePUCCH transmission during the common ePUCCH opportunity.

In yet another exemplary embodiment of a MSF grant, multicarriertransmission aspects may be taken into account for the MSF grant. Ifmultiple UL carriers are available, then a single MSF grant may be usedto indicate the scheduling sequence of PUSCH and ePUCCH transmissionsacross multiple UL carriers in parallel. The overall duration of thetransmission sequences on the different UL carriers may be different,although they may start from the same subframe. For example, with thesame MSF grant, on carrier 1 the UE may be scheduled to transmit N1PUSCH+ePUCCH subframes, while on carrier 2 the UE may be scheduled totransmit N2 PUSCH+ePUCCH subframes. For each UL carrier, the schedulingindication may be performed using bit sequences as described above forprevious embodiments. The knowledge of the sequence lengths may berequired per carrier to tell the UE in which subframes to transmit,while the other scheduling information in the grant may tell the UE howto transmit (what MCS, redundancy version, etc.).

FIG. 12 is a schematic representation of a network node 1200 accordingto an exemplary embodiment of the present invention. The network node1200 may include a receiver 1202, a transmitter 1204, at least oneprocessor 1206 or processing circuitry, and a memory 1208 that maycontain instructions for performing methods according to exemplaryembodiments of the present invention. FIG. 13 is a schematicrepresentation of a wireless device 1300 according to an exemplaryembodiment of the present invention. The wireless device 1300 mayinclude a receiver 1302, a transmitter 1304, at least one processor 1306or processing circuitry, and a memory 1308 including instructions forperforming methods according to exemplary embodiments of the presentinvention.

FIG. 14 is a flowchart of an exemplary method 1400 implemented by thewireless device 1300 of FIG. 13 according to an exemplary embodiment ofthe present invention. In operation 1402, the wireless device 1300 mayreceive via receiver 1302 an uplink grant from a network node 1200indicating to the wireless device 1300 at least one data subframe and atleast one control subframe. The uplink grant may a UE-specificmulti-subframe UL grant. A data subframe may be one where the wirelessdevice is scheduled to transmit a channel for carrying a data stream andoptional control data. For example, a data subframe may be a subframewhere the wireless device is scheduled to transmit a PUSCH. A controlsubframe may be one where the wireless device is scheduled to transmit achannel for carrying control data only. For example, a control subframemay be a subframe where the wireless device is scheduled to transmiteither a PUCCH or a ePUCCH. In operation 1404, the wireless device 1300may transmit via the transmitter 1304 in at least some of the subframesindicated by the uplink grant.

The uplink grant may comprise grant information describing a sequencecomposed of data subframes and control subframes. The grant informationmay indicate for each subframe in the sequence whether it is a datasubframe or a control subframe. Each subframe in the sequence may beassociated with a value in the grant information indicating whether thesubframe is a data subframe or a control subframe. Each subframe in thesequence may be associated with a value in the grant informationindicating whether to include in the subframe a time gap foraccommodating a listen-before-talk procedure. Each subframe in thesequence may be associated with two independently assignable values, thefirst of which being the value indicating whether the subframe is a datasubframe or a control subframe, and the second of which being the valueindicating whether to include in the subframe a time gap foraccommodating a listen-before-talk procedure.

The method 1400 may further include the operation of receiving on aseparate control channel, such as C PUCCH, an indication whether toinclude in a subframe a time gap for accommodating a listen-before-talkprocedure.

As noted above, the sequence of data subframes and control subframes maybe implicitly described by the grant information in one embodiment. Theimplicit description of the sequence may be based on an agreement as tothe location of a control subframe relative to the location of a datasubframe or a range of data subframes. The implicit description of thesequence may be based on an agreement that a contiguous range ofsubframes is described in terms of its start and end. For example, themulti subframe grant may explicitly indicate the locations of PUSCHsubframes using a bitmap. As another example, the MSF grant may indicatea range of start and end subframes. In such examples, the UE may inferthe ePUCCH location to be, for example, in the subframe after the lastPUSCH transmission, or alternatively before the first PUSCH subframe.The sequence described by the grant information may begin apredetermined number of subframes after a subframe containing the uplinkgrant.

In another embodiment noted above, the uplink grant may compriseactivation information indicating to the wireless device whether apredefined transmission opportunity is a control subframe. Thepredefined transmission opportunity may be indicated in advance bysignaling received on a control channel common to a plurality ofwireless devices. The control channel common to a plurality of wirelessdevices may be cell-specific. For example, the location of an ePUCCHsubframe opportunity may be determined based on cell-specific C-PDCCHand may be common for all UEs. In such an example, a UE-specific MSFgrant may indicate to a particular UE if it should transmit or suppressits ePUCCH transmission.

In yet another embodiment described above, the wireless device may beadapted for multicarrier operation and the uplink grant may relate tocontemporaneous transmissions on multiple uplink carriers. For example,a single MSF grant may be used to indicate the scheduling sequence ofPUSCH and ePUCCH transmissions across multiple UL carriers in parallel.The uplink grant may contain multicarrier information indicating foreach uplink carrier a total length of a sequence composed of datasubframes and control subframes on that uplink carrier.

The method 1400 may further comprise the operation of initiallytransmitting a scheduling request to the network node 1200.

FIG. 15 is a flowchart of an exemplary method 1500 implemented by thenetwork node 1200 of FIG. 12 according to an exemplary embodiment of thepresent invention. In operation 1502, the transmitter 1204 may transmitan uplink grant (e.g., a UE-specific multi-subframe UL grant) indicatingto a wireless device 1300 at least one data subframe and at least onecontrol subframe. A data subframe may be one where the wireless deviceis scheduled to transmit a channel for carrying a data stream andoptional control data (e.g., PUCCH), and a control subframe may be onewhere the wireless device is scheduled to transmit a channel forcarrying control data only (e.g., PUCCH or ePUCCH). In operation 1504,the network node 1200 may receive via receiver 1302, from a wirelessdevice 1300 having received the uplink grant, transmissions in thesubframes indicated by the uplink grant.

The uplink grant may comprise grant information describing a sequencecomposed of data subframes and control subframes. The grant informationmay indicate for each subframe in the sequence whether it is a datasubframe or a control subframe. Each subframe in the sequence may beassociated with a value in the grant information indicating whether thesubframe is a data subframe or a control subframe. Each subframe in thesequence may be associated with a value in the grant informationindicating whether to include in the subframe a time gap foraccommodating a listen-before-talk procedure. Each subframe in thesequence may be associated with two independently assignable values, thefirst of which being the value indicating whether the subframe is a datasubframe or a control subframe, and the second of which being the valueindicating whether to include in the subframe a time gap foraccommodating a listen-before-talk procedure.

The method 1500 may further include the operation of transmitting on aseparate control channel, such as C PUCCH, an indication whether toinclude in a subframe a time gap for accommodating a listen-before-talkprocedure.

In one embodiment, the sequence of data subframes and control subframesmay be implicitly described by the grant information. The implicitdescription of the sequence may be based on an agreement as to thelocation of a control subframe relative to the location of a datasubframe or a range of data subframes. The implicit description of thesequence may be based on an agreement that a contiguous range ofsubframes is described in terms of its start and end. The sequencedescribed by the grant information may begin a predetermined number ofsubframes after a subframe containing the uplink grant.

In another embodiment, the uplink grant may comprise activationinformation indicating to the wireless device whether a predefinedtransmission opportunity is a control subframe. The predefinedtransmission opportunity may be indicated in advance by signalingtransmitted on a control channel common to a plurality of wirelessdevices. The control channel common to a plurality of wireless devicesmay be cell-specific.

In yet another embodiment, the wireless device may be adapted formulticarrier operation and the uplink grant may relate tocontemporaneous transmissions on multiple uplink carriers. The uplinkgrant may contain multicarrier information indicating for each uplinkcarrier a total length of a sequence composed of data subframes andcontrol subframes on that uplink carrier.

The method 1500 may further comprise the operation of initiallyreceiving a scheduling request from the wireless device, wherein theuplink grant is transmitted in response to receipt of said schedulingrequest.

In one or more of the embodiments described herein, the uplink grant maybe contained in one subframe. The subframe may have a duration of 1 msor a duration of the order of 1 ms.

The uplink grant may comprise, in addition to the indication of at leastone data subframe and at least one control subframe, one or more of thefollowing: resource/interlace assignment and frequency hopping flag;carrier indicator for cross-carrier scheduling; Modulation and CodingScheme (MCS); New Data Indicator (NDI); hybrid automatic retransmissionrequest (HARQ) information and Redundancy Version (RV); power controlcommand for scheduled PUSCH; cyclic shift for uplink demodulationreference signal (DMRS); flag bits or bit sequences to configuresubframes with a time gap for accommodating a listen-before-talkprocedure; request for transmission of an aperiodic channel qualityindex (CQI) report or aperiodic sounding reference signal (SRS)transmission.

The data subframes and control subframes may be transmitted on alisten-before-talk-based carrier, such as unlicensed spectrum. A datasubframe may be used to transmit a shared channel, such as PUSCH asspecified in 3GPP LTE. A control subframe may be used to transmit any ofPUCCH or ePUCCH as specified in 3GPP LTE. The uplink grant may betransmitted on PDCCH as specified in 3GPP LTE

Embodiments of the present invention can also be expressed in terms ofhardware and software modules. For example, a wireless device and/or anetwork node may include an uplink scheduling module, an uplink grantreception module, and a gap creation module. The modules may beimplemented in hardware, software (e.g., software stored in a computerreadable medium such as a non-transitory computer readable medium (e.g.,memory)) and executed by one or more processors. The modules may operateto provide the functionality of the network nodes and the wirelessdevices according to one or more of the embodiments described herein.

In view of the above, embodiments are proposed for using a singlemulti-subframe UL grant to schedule a sequence of both UL data andcontrol channel transmissions.

The embodiments can provide various advantages. For example, by using asingle, UE-specific multi-subframe UL grant to schedule a sequence ofPUSCH and PUCCH transmissions, there is no need for introducingadditional gaps for DL and UL LBT. Additionally, the embodiments provideimproved UL throughput, decreased control overhead, and reduced risk oflosing channel access to Wi-Fi or other LAA nodes.

Moreover, while it is possible to transmit UCI on PUSCH instead ofePUCCH, the ePUCCH is designed to multiplex multiple UEs on the sameinterlace, and therefore is more efficient in terms of resource usagefor UCI transmission.

It should be understood that this description is not intended to limitthe invention. On the contrary, the embodiments are intended to coveralternatives, modifications and equivalents, which are included in thespirit and scope of the claims. Further, in the detailed description ofthe embodiments, numerous specific details are set forth in order toprovide a comprehensive understanding of the invention. However, oneskilled in the art would understand that various embodiments may bepracticed without such specific details.

Although the features and elements of the present embodiments aredescribed in the embodiments in particular combinations, each feature orelement can be used alone without the other features and elements of theembodiments or in various combinations with or without other featuresand elements disclosed herein.

This written description uses examples of the subject matter disclosedto enable any person skilled in the art to practice the same, includingmaking and using any devices or systems and performing any incorporatedmethods. The patentable scope of the subject matter may include otherexamples that occur to those skilled in the art. Such other examples areintended to be within the scope of the present application.

1. A method implemented in a wireless device, comprising: receiving anuplink grant from a network node indicating to the wireless device atleast one data subframe and at least one control subframe, wherein theat least one data subframe is one where the wireless device is scheduledto transmit a channel for carrying a data stream and optional controldata, and the at least one control subframe is one where the wirelessdevice is scheduled to transmit a channel for carrying control dataonly; and transmitting in at least one of the at least one data subframeand the at least one control subframe indicated by the uplink grant. 2.The method of claim 1, wherein the uplink grant comprises grantinformation describing a sequence composed of data subframes and controlsubframes.
 3. The method of claim 2, wherein the grant informationindicates for each subframe in the sequence whether it is a datasubframe or a control subframe.
 4. The method of claim 2, wherein eachsubframe in the sequence is associated with a value in the grantinformation indicating whether the subframe is a data subframe or acontrol subframe.
 5. The method of claim 2, wherein each subframe in thesequence is associated with a value in the grant information indicatingwhether to include in the subframe a time gap for accommodating alisten-before-talk procedure.
 6. The method of claim 5, wherein eachsubframe in the sequence is associated with two independently assignablevalues in the grant information, the first of which being the valueindicating whether the subframe is a data subframe or a controlsubframe, and the second of which being the value indicating whether toinclude in the subframe a time gap for accommodating alisten-before-talk procedure.
 7. The method of claim 2, furthercomprising: receiving on a separate control channel an indicationwhether to include in a subframe a time gap for accommodating alisten-before-talk procedure.
 8. The method of claim 2, wherein thesequence of data subframes and control subframes is implicitly describedby the grant information.
 9. The method of claim 8, wherein the implicitdescription of the sequence is based on an agreement as to the locationof a control subframe relative to the location of a data subframe or arange of data subframes.
 10. The method of claim 9, wherein the implicitdescription of the sequence is based on an agreement that a contiguousrange of subframes is described in terms of a start and end of thecontiguous range.
 11. The method of claim 2, wherein the sequencedescribed by the grant information begins a predetermined number ofsubframes after a subframe containing the uplink grant.
 12. The methodof claim 1, wherein the uplink grant comprises activation informationindicating to the wireless device whether a predefined transmissionopportunity is a control subframe.
 13. The method of claim 12, whereinthe predefined transmission opportunity is indicated in advance bysignaling received on a control channel common to a plurality ofwireless devices.
 14. The method of claim 13, wherein the controlchannel common to the plurality of wireless devices is cell-specific.15. The method of claim 1, wherein the wireless device is adapted formulticarrier operation and the uplink grant relates to contemporaneoustransmissions on multiple uplink carriers.
 16. The method of claim 15,wherein the uplink grant contains multicarrier information indicatingfor each uplink carrier a total length of a sequence composed of datasubframes and control subframes on that uplink carrier.
 17. The methodof claim 1, further comprising: initially transmitting a schedulingrequest to the network node.
 18. A wireless device comprising: areceiver; a transmitter; at least one processor; and a memory storinginstructions executable by the at least one processor for: receiving,using the receiver, an uplink grant from a network node indicating tothe wireless device at least one data subframe and at least one controlsubframe, wherein the at least one data subframe is one where thewireless device is scheduled to transmit a channel for carrying a datastream and optional control data, and the at least one control subframeis one where the wireless device is scheduled to transmit a channel forcarrying control data only; and transmitting, using the transmitter, inat least one of the at least one data subframe and the at least onecontrol subframe indicated by the uplink grant. 19.-37. (canceled)
 38. Anetwork node comprising a receiver, a transmitter, at least oneprocessor and a memory storing instructions executable by the at leastone processor for: transmitting, using the transmitter, an uplink grantindicating to a wireless device at least one data subframe and at leastone control subframe, wherein the at least one data subframe is onewhere the wireless device is scheduled to transmit a channel forcarrying a data stream and optional control data, and the at least onecontrol subframe is one where the wireless device is scheduled totransmit a channel for carrying control data only; and receiving, usingthe receiver, from a wireless device having received the uplink grant,transmissions from the wireless device in the at least one data subframeand the at least one control subframe indicated by the uplink grant.39.-41. (canceled)
 42. The method of claim 1, wherein the uplink grantis contained in one subframe.
 43. (canceled)
 44. The method of claim 1,wherein the uplink grant comprises, in addition to the indication of atleast one data subframe and at least one control subframe, one or moreof the following: resource/interlace assignment and frequency hoppingflag; carrier indicator for cross-carrier scheduling; Modulation andCoding Scheme (MCS); New Data Indicator (NDI); hybrid automaticretransmission request (HARQ) information and Redundancy Version (RV);power control command for scheduled PUSCH; cyclic shift for uplinkdemodulation reference signal (DMRS); flag bits or bit sequences toconfigure subframes with a time gap for accommodating alisten-before-talk procedure; request for transmission of an aperiodicchannel quality index (CQI) report or aperiodic sounding referencesignal (SRS) transmission.
 45. The method of claim 1, wherein the uplinkgrant comprises, in addition to the indication of at least one datasubframe and at least one control subframe, one or more of a request fora channel state information (CSI) report and hybrid automaticretransmission request (HARQ) information.
 46. The method of claim 1,wherein the at least one data subframe and the at least one controlsubframe are to be transmitted on a listen-before-talk-based carrier,such as unlicensed spectrum.
 47. The method of claim 1, wherein the atleast one data subframe is used to transmit a shared channel. 48.(canceled)
 49. The method of claim 1, wherein the at least one controlsubframe is used to transmit any of a physical uplink control channel(PUCCH) or extended PUCCH (ePUCCH) as specified in 3GPP LTE.
 50. Themethod of claim 1, wherein the uplink grant is transmitted on a physicaldownlink control channel (PDCCH) as specified in 3GPP LTE.
 51. Themethod of claim 7, wherein the separate control channel comprises aC-physical uplink control channel (C-PUCCH).
 52. (canceled)
 53. Themethod of claim 2, wherein the sequence composed of data subframes andcontrol subframes comprises four total subframes.
 54. The method ofclaim 53, wherein the sequence composed of data subframes and controlsubframes comprises three data subframes and one control subframe. 55.(canceled)
 56. (canceled)
 57. The method of claim 2, wherein thesequence composed of data subframes and control subframes compriseseight or ten total subframes.
 58. (canceled)